Theoretical studies on iron surface coating: adsorption of furan derivatives over Fe(n) clusters (n = 1-4).

: In the transition from small molecules to solids, atomic clusters are studied widely not only because they can own unique properties due to the nanosized effect but also because they represent an intermediate stage. A systematic study on the structures and properties of clusters as a function of size could give information on the transition from clusters to bulk and determine at what size a cluster can mimic the bulk solid at least to some extent. The adsorption capability of furan derivatives 2-furfurylamine, 2-furfuryl alcohol and 2-furfuryl mercaptan with different iron-clusters was studied by DFT. The results show that since the compounds possess suitable structural and electronic parameters for the metal adhesion, it is observed that the functional group (NH2, OH and SH) of furan derivatives strongly adsorb over the metal clusters. Moreover, the calculated binding energy supports the existence of a bond between furan derivatives and metal, indicating the transfer of high charge density which in the delocalization region of furan ring to the metal (L(sigma) --> Fe). In the molecular orbital studies by detecting the overlap of HOMO (furan ring and functional group) with LUMO (iron), the binding nature of the compounds is then confirmed.